The way to monetize F2P SC2 gaming is through maps. Naturally, you want your SC2 client to easily and painlessly present new maps to SC2 players when they boot up SC2, and downloads should be fast and hassle-free. It needs to "just work."

Most importantly, Blizz needs talented people working on map design and a small community of good testers. An Internet shop near our place kept things fresh (especially for MP Starcraft) by introducing new, interesting, and fun maps every week.

A robust map-making community could be all that's needed to spawn the next round of RTS-derived game design (currently, those include Tower Defense games and MOBA games).